Welded double fabric tube

ABSTRACT

A fabric tube with two passages comprises a fabric tube sheet. A first fabric weld strip with right and left flanges extending laterally from a bottom edge of a weld fin is welded to a first surface extending the length of the fabric tube sheet at a distance D 1  from the first edge thereof. A second fabric weld strip is welded to an opposite second surface and extends the length of the fabric tube sheet between the first fabric weld strip and the second edge of the fabric tube sheet at a distance D 2  from the second edge of the fabric tube sheet. The first edge of the fabric tube sheet is welded to the weld fin of the second fabric weld strip and the second edge of the fabric tube sheet is welded to the weld fin of the first fabric weld strip to form two passages.

RELATED APPLICATIONS

This application claims priority to Canadian Application No.: 2,770,876,filed on Mar. 8, 2012. The entire teachings of the above application areincorporated herein by reference.

TECHNICAL FIELD

This invention is in the field of fabric tubes and in particular adouble fabric tube with welded seams such as could be used as an airduct in ventilation applications. The tube could also be sealed andfilled with water to act as a containment vessel or alternately, act asa flood barrier that resists displacement by rising flood waters.

BACKGROUND

Fabric tubes are well known for use as ducts to move air in largebuildings, such as industrial plants and the like, as same can be moreeconomical and quicker to install than metal ducts. Such fabric tubesare also commonly used in construction and similar temporary structureapplications, as they are relatively light weight, economical, and easyto install, typically by hanger from the ceiling. Because of the lightweight, the hangers do not need to be particularly strong, and can befairly widely spaced.

Fabric tubes have also been commonly used as ducts to carry ventilationair long distances, such as in underground mines. Such tubes commonlyinclude a hanger strip attached along a top of the tube with grommetholes defined therein to receive hangers attached to the ceiling of amine passageway. As headroom in mine passageways may be limited, it isalso known to provide fabric tubes with two side by side passageways toincrease air flow capacity without increasing the diameter and furtherencroaching on available headroom. Such a double tube is disclosed forexample in U.S. Pat. No. 5,094,273 to Eagleton.

Fabric tubes may be formed by welding or by sewing. While welding isgenerally more expensive and slower, welded seams are generally strongerthan a sewn seam. With proper equipment, welded seam strengths canapproach strengths recorded in the finished fabric. Ventilationengineers often qualify fabric tubes based on a pressure rating or themaximum working pressure of the air carried in the tube. The amount ofventilation air that can be moved through a tube is dependent on thepressure of the air generated by large diameter, high horsepower fans,with a higher pressure typically resulting in a higher volume of airmoved and a reduction in electricity used. It is generally desirable tomove as much air as possible in a given size tube, and so the pressurerating is an important factor when selecting a tube for a ventilationapplication. Welded seams are commonly used where higher air pressureswill be used as there are no needle perforations for air leakage and invery high pressure applications, no potential for weakening anddisintegration as the needle perforations expand from the pressureassociated with the volume of air be pushed through the tube.

It is also known to fill a sealed fabric tube with water and positionthe filled tube as a flood control barrier as disclosed in U.S. Pat. No.5,865,564 to Miller et al. The Miller tube is similar to a side by sidedouble tube comprising a large tube with a divider flap welded acrossthe middle that pulls the tube together as well as dividing it, and thatresults in an oblong cross section resting on a flat side that resistsrolling in response to the pressure of flood waters being held at bay.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a double fabric tubethat overcomes problems in the prior art.

In a first embodiment the present invention provides a fabric tube withtwo passages. The tube comprises a fabric tube sheet with a lengthbetween opposite first and second ends thereof, a width between oppositefirst and second substantially parallel edges thereof, a first surface,and a second surface opposite the first surface. A first fabric weldstrip comprises right and left flanges extending laterally from a bottomedge of a weld fin and welded to the first surface such that the weldfin thereof extends from the first surface. The first fabric weld stripextends from the first end to the second end of the fabric tube sheet ata selected first distance D1 from the first edge of the fabric tubesheet. A second fabric weld strip comprises right and left flangesextending laterally from a bottom edge of a weld fin and welded to thesecond surface such that the weld fin thereof extends from the secondsurface. The second fabric weld strip extends along the second surfacefrom the first end to the second end of the fabric tube sheet betweenthe first fabric weld strip and the second edge of the fabric tube sheetat a selected second distance D2 from the second edge of the fabric tubesheet. The first edge of the fabric tube sheet is welded to the weld finof the second fabric weld strip and the second edge of the fabric tubesheet is welded to the weld fin of the first fabric weld strip to formtwo passages.

In a second embodiment the present invention provides a method of makinga fabric tube with two passages. The method comprises providing a fabrictube sheet with a length L between opposite first and second endsthereof, a width W between opposite first and second substantiallyparallel edges thereof, a first surface, and a second surface oppositethe first surface; providing a first fabric weld strip comprising rightand left flanges extending laterally from a bottom edge of a weld finand welded to the first surface such that the weld fin thereof extendsfrom the first surface and such that the first fabric weld strip extendsfrom the first end to the second end of the fabric tube sheet at aselected first distance D1 from the first edge of the fabric tube sheet;providing a second fabric weld strip comprising right and left flangesextending laterally from a bottom edge of a weld fin and welded to thesecond surface such that the weld fin thereof extends from the secondsurface and such that the second fabric weld strip extends along thesecond surface from the first end to the second end of the fabric tubesheet between the first fabric weld strip and the second edge of thefabric tube sheet at a selected second distance D2 from the second edgeof the fabric tube sheet; when the first and second fabric weld stripshave been welded to the fabric tube sheet to form a fabric tube sheetwith weld strips, welding the first edge of the fabric tube sheet to theweld fin of the second fabric weld strip and welding the second edge ofthe fabric tube sheet to the weld fin of the first fabric weld strip toform two passages.

The configuration of the welds with ends of the fabric tube sheet weldedto fins of the fabric weld strips such that the weld is in tension, andwith two welds holding the flanges to the sheet provides increasedstrength compared to simply folding a strip of the end of the sheet andwelding same to the fabric. Thus increased air pressure can be carriedin the tube.

When sewing seams for higher pressures, three needle sewing machinesproduced sewn seams on folded over 2 or 3 ply fabric with webbingreinforcement, in order to have some strength at the seams to addressthe pressure of the air going through the tube and avoid prematurefailure or disintegration over time.

The fabric tube of the present invention can be used as a duct to carryair in ventilation applications, and can also be readily sealed at theends thereof and filled with water as a flood barrier. It is alsocontemplated that a sealed tube of the present invention could be usedas a storage vessel for various fluids.

DESCRIPTION OF THE DRAWINGS

While the invention is claimed in the concluding portions hereof,preferred embodiments are provided in the accompanying detaileddescription which may be best understood in conjunction with theaccompanying diagrams where like parts in each of the several diagramsare labeled with like numbers, and where:

FIG. 1 is a schematic end view of a fabric tube sheet with weld stripslaying flat and then folded and welded into an embodiment of a tube ofthe present invention;

FIG. 2 is a schematic top view of the fabric tube sheet of FIG. 1;

FIG. 3 is schematic sectional end view of the fabric weld strip andsheet end of the fabric tube sheet with weld strips of FIG. 1;

FIG. 4 is a schematic end view of the tube of FIG. 1 with hanger stripsattached;

FIG. 5 is a schematic end view showing the force exerted on the fabricweld strip and the welds holding the fabric weld strip to the fabrictube sheet;

FIG. 6 is a schematic end view showing the force exerted on aconventional folded and welded fabric seam;

FIG. 7 is a schematic top view showing the fabric tube sheet with weldstrips of FIG. 1;

FIGS. 8 and 9 are schematic top and end views respectively showing theassembly of the fabric tube sheet with weld strips of FIG. 1 from aninitial fabric tube sheet of twice the length with a fabric weld stripwelded to one surface thereof.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

FIGS. 1 and 2 schematically illustrate an embodiment of a fabric tube 1of the present invention with two passages as shown in dotted lines inFIG. 1 and the fabric tube sheet 3 that is first formed to make the tube1. The fabric tube sheet 3 has a length L between opposite fore and aftends 3A, 3B thereof, a width W between opposite right and left paralleledges 3R, 3L thereof. The fabric tube sheet 3 has a top surface 5, and abottom surface 7 opposite the top surface 5.

First and second fabric weld strips 9A, 9B each comprise, asschematically illustrated in FIG. 3, right and left flanges 11 extendinglaterally from a bottom edge of a weld fin 13 that are welded to asurface of the fabric tube sheet 3. In the illustrated embodiment, thefabric weld strips 9A, 9B are made by folding a fabric strip 15 over afin reinforcing strip 17. The fin reinforcing strip 17 is typicallyanother fabric strip, which may be heavier than the fabric of the fabricstrip 15 or fabric tube sheet 3. The fabric strip 15 is welded to thefin reinforcing strip 117 on each side thereof such that the weld fin 13is formed by two layers of the fabric strip 15 with the fin reinforcingstrip 17 welded between them. The flanges 11 are provided by a singlelayer of the fabric strip 15 extending laterally from a bottom edge ofthe fin reinforcing strip 17. It is contemplated that otherconfigurations of the fabric weld strips 9 could be used to provide theflanges 11 and weld fin 13 required to practice the present invention.

The flanges 11 of the first fabric weld strip 9A are welded to the topsurface 5 such that the weld fin 13 thereof extends from the top surface5 as illustrated, and such that the first fabric weld strip 9A extendsfrom the fore end 3A to the aft end 3B of the fabric tube sheet 3 at aselected first distance D1 from the right edge 3R of the fabric tubesheet 3.

The flanges 11 of the second fabric weld strip 9B are welded to thebottom surface 7 of the fabric tube sheet 3 such that the weld fin 13thereof extends from the bottom surface 7. The second fabric weld strip9B also extends from the fore end 3A to the aft end 3B of the fabrictube sheet 3 at a selected second distance D2 from the left edge 3L ofthe fabric tube sheet 3.

To form the tube 1, the respective edges 3R, 3L of the fabric tube sheet3 are welded to the weld fins 13 as schematically shown in FIG. 3. Whenthe first and second fabric weld strips 9A, 9B have been welded toopposite surfaces 5, 7 of the fabric tube sheet 3, the right edge 3R ofthe fabric tube sheet 3 is folded down as shown in the dotted lines inFIG. 1 and welded to the weld fin 13 of the second fabric weld strip 9Band the left edge 3L of the fabric tube sheet 3 is folded up as shown inthe dotted lines in FIG. 1 and welded to the weld fin 13 of the firstfabric weld strip 9A to form two passages 19.

The pressure of ventilation air in the tube 1 exerts a force F at thefabric weld strips 9, as illustrated schematically in FIG. 5. The fabricweld strips 9 are joined to the fabric tube sheet 3 by a weld 25 on eachflange 11. Thus the force F tending to pull the fabric weld strip 9 awayfrom the fabric tube sheet 3 is resisted by two welds 25. The force Falso tends to pull the edges 3A, 3B of the fabric tube sheet 3 away fromits connection to the weld fin 13 at weld 27. This weld 27 however is intension, with direct lateral force on the weld 27.

A weld in lateral tension as in the present tube 1 can resist a greaterforce F than can a weld that is subjected to a peeling force asschematically illustrated in FIG. 6, where the sheet end 31A is simplyfolded against the sheet 31 and welded at weld 33. It can be seen thatthe force F is resisted only by the edge 35 of the weld 33. As the edge35 of the weld 33 gives way, the force F moves progressively across theweld 33. In contrast in the weld 27 subjected to tension, the force F isresisted by the entire width of the weld 27, as the entire weld 27 mustseparate at the same time.

In the illustrated tube 1, the distance D1 is substantially the same asthe distance D2 such that the two passages are substantially the samesize. Varying the location of the fabric weld strips 9 can vary therelative sizes of the passages 19 if for a particular application it isdesired to have one passage 19 larger than the other.

The illustrated tube 1 further has a plurality of apertures 21 definedin the fabric tube sheet 3 between the first and second fabric weldstrips 9A 9B such that air can pass between the two passages 19 toequalize pressure therebetween.

FIG. 4 illustrates a typical orientation of the tube 1 as it would behung from the ceiling of a mine passageway with the passages 19 side byside. To conveniently accomplish this a first hanger strip 23A is weldedto the top surface 5 of the fabric tube sheet 3 between the right edge3R of the fabric tube sheet 3 and the first fabric weld strip 9A at adistance D3 from the first fabric weld strip 9A, and a second hangerstrip 23B is welded to the bottom surface 7 of the fabric tube sheet 3between the left edge 3L of the fabric tube sheet 3 and the secondfabric weld strip 9B at a distance D4 from the left edge 3L of thefabric tube sheet 3.

The distances D3 and D4 are selected such that the passages 19 aresubstantially side by side as shown in FIG. 4 when the tube 1 is hangingfrom the first and second hanger strips 23A, 23B. In the illustratedtube 1 of FIG. 4, the distance D3 is substantially equal to the distanceD4 and the hangers 23A, 23B are substantially at the top of each passage19 such that the tube 1 hangs as illustrated.

The invention thus provides a method of making a fabric tube 1 with twopassages as described above and in FIGS. 7-9. The method comprisesproviding a fabric tube sheet 3 with a length L between opposite firstand second ends 3A, 3B thereof, a width W between opposite right andleft substantially parallel edges 3R, 3L thereof, a first surface 5, anda second surface 7 opposite the first surface; providing a first fabricweld strip 9A and welding same to the first surface 5 such that sameextends from the first end 3A to the second end 3B of the fabric tubesheet 3 at a selected first distance D1 from the right edge 3R of thefabric tube sheet 3; providing a second fabric weld strip 9B and weldingsame to the second surface 7 such that same extends along the secondsurface from the first end 3A to the second end 3B of the fabric tubesheet 3 between the first fabric weld strip 9A and the left edge 3L ofthe fabric tube sheet 3 at a selected second distance D2 from the leftedge 3L; when the first and second fabric weld strips 9A, 9B have beenwelded to the fabric tube sheet 3 to form a fabric tube sheet with weldstrips 40 as shown in FIG. 7, welding the right edge 3R of the fabrictube sheet 3 to the weld fin 13 of the second fabric weld strip 9B andwelding the left edge 3L of the fabric tube sheet 3 to the weld fin 13of the first fabric weld strip 9A to form two passages 19.

It may be desirable to weld the fabric weld strips 9 onto the fabrictube sheet in one continuous operation. To accomplish this, the fabrictube sheet with weld strips 40 can be provided by providing an initialfabric sheet 41 with a top surface 47 and a bottom surface 49, theinitial fabric sheet 41 having a length 2L between opposite fore and aftends 41A, 41B thereof that is substantially equal to two times thelength L of the desired fabric tube sheet 3 and a width 0.5 W+SW betweenfirst and second edges 43A, 43B thereof that is equal to one half thewidth W of the fabric tube sheet 3 plus a seam width SW. An initialfabric weld strip 45 is welded to the top surface 47 such that theinitial fabric weld strip 41 extends from the fore end 41A to the aftend 41B of the initial fabric tube sheet 41 at the selected firstdistance Di from the first edge 43A of the fabric tube sheet 3.

The initial fabric sheet 41 is cut across the width thereof from thefirst edge 43A to the second edge 43B thereof at a midpoint of thelength 21 thereof to form fore and aft sheet portions 51, 53 each with alength substantially equal to the length L of the fabric tube sheet 3.The fore sheet 51 is turned over such that the top surface 47 thereoffaces downward and the fore and aft sheet portions 51, 53 are orientedside by side as indicated by the dotted lines such that the second edge43B of the fore sheet portion 51 and the second edge 43B of the aftsheet portion 53 overlap by the seam width SW. The fore and aft sheets51, 53 are then welded together along the seam width SW to form thefabric tube sheet with weld strips 40. In use the weld along the seamwidth SW is in tension and thus provides a strong bond as describedabove for weld 27.

The fabric tube sheet 3 then comprises a left side portion 51 and aright side portion 53 welded together at the seam SW located between thefirst and second weld strips 9A, 9B and substantially equidistant fromthe first and second fabric weld strips.

The present invention thus provides a double tube 1 with welded seamsthat can carry significant air pressure or alternatively, form twochambers that can hold water or other fluids under pressure. The seamscomprise two welds 25 holding the fabric weld strips 9 to the fabrictube sheet 3, and a single weld 27 that is in tension holding the end ofthe fabric tube sheet 3 to the weld fin 13. The tube 1 can convenientlybe made from a single fabric sheet with a fabric weld strip welded oneach surface thereof, or with a fabric weld strip welded on one surfaceof a fabric sheet that is then cut in half and turned over and welded toform the fabric tube sheet with weld strips 40 that can then be foldedas described with the ends welded to the weld fins.

The foregoing is considered as illustrative only of the principles ofthe invention. Further, since numerous changes and modifications willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed, and accordingly, all such suitable changes or modificationsin structure or operation which may be resorted to are intended to fallwithin the scope of the claimed invention.

What is claimed is:
 1. A fabric tube with two passages, the tubecomprising: a fabric tube sheet with a length between opposite first andsecond ends thereof, a width between opposite first and secondsubstantially parallel edges thereof, a first surface, and a secondsurface opposite the first surface; a first fabric weld strip comprisingright and left flanges extending laterally from a bottom edge of a weldfin and welded to the first surface such that the weld fin thereofextends from the first surface; wherein the first fabric weld stripextends from the first end to the second end of the fabric tube sheet ata selected first distance D1 from the first edge of the fabric tubesheet; a second fabric weld strip comprising right and left flangesextending laterally from a bottom edge of a weld fin and welded to thesecond surface such that the weld fin thereof extends from the secondsurface; wherein the second fabric weld strip extends along the secondsurface from the first end to the second end of the fabric tube sheetbetween the first fabric weld strip and the second edge of the fabrictube sheet at a selected second distance D2 from the second edge of thefabric tube sheet; wherein the first edge of the fabric tube sheet iswelded to the weld fin of the second fabric weld strip and the secondedge of the fabric tube sheet is welded to the weld fin of the firstfabric weld strip to form two passages.
 2. The tube of claim 1 whereinthe distance D1 is substantially the same as the distance D2 such thatthe two passages are substantially the same size.
 3. The tube of claim 1wherein the first fabric weld strip is made by folding a fabric stripover a fin reinforcing strip and welding same such that the weld fin ofthe first fabric weld strip is formed by two layers of the fabric stripwith the fin reinforcing strip welded between them, and the flanges areprovided by a single layer of the fabric strip extending laterally froma bottom edge of the fin reinforcing strip.
 4. The tube of claim 1wherein the fabric tube sheet comprises right and left side portionswelded together at a seam located between the first and second weldstrips and substantially equidistant from the first and second fabricweld strips.
 5. The tube of claim 1 comprising a plurality of aperturesdefined in the fabric tube sheet between the first and second fabricweld strips such that fluid can pass between the two passages.
 6. Thetube of claim 1 comprising a first hanger strip welded to the firstsurface of the fabric tube sheet between the first edge of the fabrictube sheet and the first fabric weld strip at a distance D3 from thefirst fabric weld strip, and a second hanger strip welded to the secondsurface of the fabric tube sheet between the second edge of the fabrictube sheet and the second fabric weld strip at a distance D4 from thesecond end of the fabric tube sheet.
 7. The tube of claim 6 wherein thedistances D3 and D4 are selected such that the passages aresubstantially side by side when the tube is hanging from the first andsecond hanger strips.
 8. The tube of claim 7 wherein the distance D3 issubstantially equal to the distance D4.
 9. A method of making a fabrictube with two passages, the method comprising: providing a fabric tubesheet with a length L between opposite first and second ends thereof, awidth W between opposite first and second substantially parallel edgesthereof, a first surface, and a second surface opposite the firstsurface; providing a first fabric weld strip comprising right and leftflanges extending laterally from a bottom edge of a weld fin and weldedto the first surface such that the weld fin thereof extends from thefirst surface and such that the first fabric weld strip extends from thefirst end to the second end of the fabric tube sheet at a selected firstdistance D1 from the first edge of the fabric tube sheet; providing asecond fabric weld strip comprising right and left flanges extendinglaterally from a bottom edge of a weld fin and welded to the secondsurface such that the weld fin thereof extends from the second surfaceand such that the second fabric weld strip extends along the secondsurface from the first end to the second end of the fabric tube sheetbetween the first fabric weld strip and the second edge of the fabrictube sheet at a selected second distance D2 from the second edge of thefabric tube sheet; when the first and second fabric weld strips havebeen welded to the fabric tube sheet to form a fabric tube sheet withweld strips, welding the first edge of the fabric tube sheet to the weldfin of the second fabric weld strip and welding the second edge of thefabric tube sheet to the weld fin of the first fabric weld strip to formtwo passages.
 10. The method of claim 9 wherein the distance Dl issubstantially the same as the distance D2 such that the two passages aresubstantially the same size.
 11. The method of claim 10 wherein thefabric tube sheet with weld strips is provided by: providing an initialfabric sheet with a top surface and a bottom surface, the initial fabricsheet having a length between opposite fore and aft ends thereof that issubstantially equal to two times the length L of the fabric tube sheetand a width between first and second edges thereof that is substantiallyequal to one half the width W of the fabric tube sheet plus a seamwidth; welding an initial fabric weld strip comprising right and leftflanges extending laterally from a bottom edge of a weld fin and weldingthe initial fabric weld strip to the top surface such that the weld finthereof extends from the top surface and such that the initial fabricweld strip extends from the fore end of the initial fabric tube sheet tothe aft end of the initial fabric tube sheet at the selected firstdistance D1 from the first edge of the fabric tube sheet; cutting theinitial fabric sheet across the width thereof from the first edge to thesecond edge thereof at a midpoint of the length thereof to form fore andaft sheet portions each with a length substantially equal to the lengthL of the fabric tube sheet; turning the fore sheet over such that thetop surface thereof faces downward and orienting the fore and aft sheetportions side by side such that the second edge of the fore sheetportion and the second edge of the aft sheet portion overlap by the seamwidth; welding the fore and aft sheets together along the scam width toform the fabric tube sheet with weld strips.
 12. The method of claim 9comprising providing the first fabric weld strip by folding a fabricstrip over a fin reinforcing strip and welding same such that the weldfin of the first fabric weld strip is formed by two layers of the fabricstrip with the fin reinforcing strip welded between them, and theflanges are provided by a single layer of the fabric strip extendinglaterally from a bottom edge of the fin reinforcing strip.
 13. Themethod of claim 9 comprising defining a plurality of apertures in thefabric tube sheet between the first and second fabric weld strips suchthat fluid can pass between the two passages.
 14. The method of claim 9comprising welding a first hanger strip to the first surface of thefabric tube sheet between the first edge of the fabric tube sheet andthe first fabric weld strip at a distance D3 from the first fabric weldstrip, and welding a second hanger strip to the second surface of thefabric tube sheet between the second edge of the fabric tube sheet andthe second fabric weld strip at a distance D4 from the second edge ofthe fabric tube sheet.
 15. The method of claim 14 wherein the distancesD3 and D4 are selected such that the passages are substantially side byside when the tube is hanging from the first and second hanger strips.16. The method of claim 15 wherein the distance D3 is substantiallyequal to the distance D4.